Biological spoilage has always been a problem with transporting fresh fish fillets to market. At present, fish, upon being caught in the ocean, are iced or immediately frozen for preservation. Upon delivery to retailers, fish shelf-life is extremely short. Not only is there loss due to spoilage but fish lose weight yield due to drip loss. Fresh fish fillets usually maintain a quality shelf-life of only a few days after cut. Methods are needed to extend the shelf-life both for the benefit of the seller and the buyer. Antibiotics such as chlortetracycline have been used to extend the shelf-life of fish fillets but are no longer allowable in the United States. A blend of fumaric acid and benzoate is available but the composition may not be particularly effective.
The preservation of edible protein as well as yield enhancement is a well studied art which has provided numerous treatment compositions. Each type of protein product, i.e. poultry, fresh meat, eggs, cheese, sausage, shell fish, frozen shrimp and fish, has peculiar biochemical compositions with different types of bacteriological problems, taste problems, and deterioration problems. There are available numerous compositions for increasing preservation and yield which at first blush appear to be similar. However, these compositions are generally useful for only one type of protein. Such compositions are commercially or technically unsuccessful or unacceptable when applied to other types of proteins. The transfer of technology from these areas to fish fillet treatment is seldom possible. For this reason, fish fillets are particularly difficult to preserve and to maintain yield. One of the problems encountered in fish fillet preservation is pH change due to bacterial growth. Since aerobic bacterial growth is prevalent during iced storage, the pH of the fillet tends to rise. This contributes to bacterial growth and flavor problems. High fat containing fish such as catfish, trout, tuna, salmon, halibut and the like are subject to rancidity as well as putrefaction. Low fat fish such as sole, cod, flounder, perch, whitefish and the like, because of their low fat content, are less susceptible to rancidity problems. Rancidity can reduce the shelf-life of the fillets, even before putrefaction. A preservative system must counteract both bacterial growth problems and organoleptic problems. A composition for preservation of shell fish is not per se operable with fish fillet. This is particularly true in the case of fresh fish which are not frozen to increase storage stability. Further, food producers, being subject to various labeling and regulatory restrictions that influence customer reaction, desire to avoid any hint of these restrictions, if possible. The more and varied the ingredients in a composition, the greater the risk of encountering a labeling or regulatory problem. A composition with fewer ingredients can provide the food processor with a clearer labeling requirement picture than a composition of many ingredients.